config.c

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/*
 * usb/gadget/config.c -- simplify building config descriptors
 *
 * Copyright (C) 2003 David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/string.h>
#include <linux/device.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>


int
usb_descriptor_fillbuf(void *buf, unsigned buflen,
        const struct usb_descriptor_header **src)
{
    u8  *dest = buf;

    if (!src)
        return -EINVAL;

    /* fill buffer from src[] until null descriptor ptr */
    for (; NULL != *src; src++) {
        unsigned        len = (*src)->bLength;

        if (len > buflen)
            return -EINVAL;
        memcpy(dest, *src, len);
        buflen -= len;
        dest += len;
    }
    return dest - (u8 *)buf;
}


int usb_gadget_config_buf(
    const struct usb_config_descriptor  *config,
    void                    *buf,
    unsigned                length,
    const struct usb_descriptor_header  **desc
)
{
    struct usb_config_descriptor        *cp = buf;
    int                 len;

    /* config descriptor first */
    if (length < USB_DT_CONFIG_SIZE || !desc)
        return -EINVAL;
    *cp = *config;

    /* then interface/endpoint/class/vendor/... */
    len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8*)buf,
            length - USB_DT_CONFIG_SIZE, desc);
    if (len < 0)
        return len;
    len += USB_DT_CONFIG_SIZE;
    if (len > 0xffff)
        return -EINVAL;

    /* patch up the config descriptor */
    cp->bLength = USB_DT_CONFIG_SIZE;
    cp->bDescriptorType = USB_DT_CONFIG;
    cp->wTotalLength = cpu_to_le16(len);
    cp->bmAttributes |= USB_CONFIG_ATT_ONE;
    return len;
}

struct usb_descriptor_header **
usb_copy_descriptors(struct usb_descriptor_header **src)
{
    struct usb_descriptor_header **tmp;
    unsigned bytes;
    unsigned n_desc;
    void *mem;
    struct usb_descriptor_header **ret;

    /* count descriptors and their sizes; then add vector size */
    for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
        bytes += (*tmp)->bLength;
    bytes += (n_desc + 1) * sizeof(*tmp);

    mem = kmalloc(bytes, GFP_KERNEL);
    if (!mem)
        return NULL;

    /* fill in pointers starting at "tmp",
     * to descriptors copied starting at "mem";
     * and return "ret"
     */
    tmp = mem;
    ret = mem;
    mem += (n_desc + 1) * sizeof(*tmp);
    while (*src) {
        memcpy(mem, *src, (*src)->bLength);
        *tmp = mem;
        tmp++;
        mem += (*src)->bLength;
        src++;
    }
    *tmp = NULL;

    return ret;
}